The invention relates to a device for carrying out a distraction and/or compression of vertebral bodies during in particular minimally invasive spinal surgery, said device comprising a first and a second extension part, which parts are in particular sleeve-shaped, at least in portions, and each have a longitudinal direction, and each of which parts can be secured on a bone anchor in a detachable but rigid and rotationally fixed manner, the bone anchors in each case being intended to be inserted or being already inserted into one of the vertebral bodies to be treated, and comprising a spreading arrangement for the extension parts.
In modern spinal surgery, in particular in minimally invasive spinal surgery where sleeve-shaped extension parts of the bone anchors, referred to as extenders, are used, the problem is often that usually adjacent vertebral bodies have to be moved away from one another (distraction) or moved towards one another (compression). The new position can then be fixed by means of osteosynthesis devices, using correction rods. There are instruments for this purpose in the prior art which are sometimes designed in a complex manner and which connect the two extension parts, which parts are rigidly connected to the bone anchors inserted into the vertebral bodies, so as to be adjustable relative to one another. The known devices are complex to produce and complicated to use.
US 2005/024928 A1 discloses a device of the type mentioned at the outset, the spreading arrangement comprising two arms which form a scissor mechanism, a threaded spindle, and an inner threaded part, which are arranged in such a way that the arms are pivoted with respect to one another when the threaded spindle is screwed in or out in relation to the inner threaded part, the pivoting being such that the two extension parts are moved towards each other or away from one another while maintaining their mutual orientation in the plane orthogonal to the longitudinal direction of one extension part.
The object of the present invention is that of developing a device of the type mentioned at the outset, by means of which device, during the distraction or compression, the mutual spacing of the vertebral bodies is changed but the mutual orientation or alignment thereof is not changed or is at least only changed slightly, and which device the surgeon can operate easily and use more flexibly than known devices.